As many Americans celebrated a child’s birth on Christmas Day, the grim news spread that an 8-year-old Guatemalan boy had died in U.S. government custody, the second child to die in the custody of U.S. Customs and Border Protection this month after none had died in more than a decade.

By day’s end, border agents had adopted new protocols to ensure children’s safety amid a wave of immigrant arrivals at the southern border. The immigration debate has led to a partial government shutdown over border wall funding and new questions about U.S. political, legal and moral responsibilities. As hundreds of thousands of government employees stay home, others will start medical checks on every migrant child in custody. That should already have been mandatory, especially for a government that tore children from parents as a policy matter until judicial intervention this year.

Some Democrats have already demanded a congressional investigation into the Christmas Eve death of 8-year-old Felipe Alonzo-Gomez. That should proceed quickly and thoroughly, along with a probe underway within the ranks of U.S. Customs and Border Protection. An independent investigation should be a first order of business for the new Democratic-controlled House when it convenes after the break. History books will be written about this. What they will say is up to politicians and to us.